Providing guidelines for testing expected inaccuracy and imprecision
is still a matter under debate. The Expert Panel of the French
Society of Clinical Chemistry has developed a protocol, which was
based on a comparative multi-centre evaluation of four instruments:
the Ciba-Corning 278, the Instrumentation Laboratory 1306, the
Nova SP 5 and the ABL 330. The purpose was to evaluate the
analytical performance and efficiency of the analysers. Another aim
was to design a valid approach for evaluating any new system. As
buffered aqueous solutions and fluorocarbon emulsions give only
partial information, tonometered blood was used at different levels
of gas mixture, even though it is both difficult and time-consuming.
Comparisons have been established on patients' blood samples with
the analysers currently used in the evaluation sites. The tests showed
that the four analysers have the same degree of precision, and interinstrument
comparisons demonstrated a very high degree of
reliability.
This analysis emphasizes that the evaluation of instruments for
pH and blood gas analysis is neither easy nor is it often done,
mainly due to the choice of a quality-control material and the
lability of the measured parameters.